Method for Producing a Polymer-Improved Pipe Element and Pipe Element and Pipe System Comprising Same

ABSTRACT

The invention relates to a method for producing a polymer-enhanced pipeline element, in particular of a fire extinguishing installation, and to a pipeline element and a pipeline system of a fire extinguishing installation. It is proposed according to the invention to provide a first a first and a second hollow body, to align in each case one encircling edge surface of the hollow bodies with one another, to weld the two hollow bodies to one another along the encircling edge surfaces such that an encircling weld seam is generated which has a root extending on the inside of the pipeline element, and to apply a polymer-based layer to the inside of the pipeline element, wherein the polymer-based layer completely covers the inside of the pipe element and the root of the weld seam.

PRIORITY CLAIM AND INCORPORATION BY REFERENCE

This application is a 35 U.S.C. § 371 application of International Application No. PCT/EP2019/067154, filed Jun. 27, 2019, which claims the benefit of German Application No. 10 2018 115 525.5, filed Jun. 27, 2018, each of which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a method for producing a polymer-enhanced pipeline element. The invention also relates to a pipeline element, in particular produced in such a method. The invention also relates to a pipeline system having such a pipeline element.

BACKGROUND AND SUMMARY OF THE INVENTION

Methods for producing pipelines for fire extinguishing installations are generally known. Pipeline elements in fire extinguishing installations are subject to the particular challenge that they are installed unused in objects for very long periods of time and, in the event of operation, must reliably and assuredly perform their task of transporting fluid.

For example, fire extinguishing installations in which the pipeline systems carry extinguishing liquid even in the standby state, and alternatively those which do not yet carry extinguishing liquid in the sprinkler lines in the standby state, are widely used. In the case of the latter systems in particular, the susceptibility to corrosion inside the pipes is a particular challenge, which is why efforts have been made in the prior art to reduce the corrosion resistance of pipeline elements, in particular for fire extinguishing installations. In order to avoid the problem of corrosion within fire extinguishing installations, alternative approaches have been developed in which large parts of the pipeline system, and with them the majority of the installed pipeline elements, are in the standby state filled not with extinguishing fluid but with gases.

The costs for the systems from the prior art are sometimes considerable, since on the one hand the use of corrosion-resistant pipes or complex passivation processes were necessary, and on the other hand high installation costs were necessary for the charging of the respective pipeline systems with gas.

EP Application 1 2153 964 which published as EP 2 623 163 A1 and EP Application 1 2798 290 which published as EP 2 766 653 each describe systems and methods which achieve a significant improvement over the prior art. Said documents describe for the first time the use of polymer enhancement by autodeposition on the inside of the pipe in pipeline elements of fire extinguishing installations. The polymer enhancement described in said documents is extremely robust owing to the attained ionic bonding of a polymer-based coating material to the pipe surface and allows the use of simple metals that are not yet corrosion-resistant per se, in particular low-alloy steel types. At the same time, very low corrosion development, to the point of complete corrosion resistance, is achieved even over relatively long observation periods.

There is nevertheless a need for further improvement in relation to the prior art. Thus, in relation to the prior art, it is sought for not only simple pipeline elements which are composed only of a tubular hollow body with one inlet and one outlet, but also pipeline elements which have multiple outlets and which are in particular made up of multiple hollow bodies, to be equipped with a polymer enhancement. The assembly of multiple hollow bodies to form complex pipeline elements is performed either by piecing the hollow bodies together using couplings, pipe connectors and the like, or by welding. It has been found that the use of pipe connectors in the region of the transition from one hollow body to the next hollow body leads to an increase in the flow resistance, which lowers the flow speed and increases resulting pressure losses, expressed by the so-called C-factor, reduces. This potentially increases the outlay on equipment required to convey the extinguishing fluid, for example in the form of the need for more powerful pumps or larger nominal pipe widths. The C-factor is calculated in accordance with generally known principles using the Hazen-Williams equation.

In the prior art, where first and second hollow bodies were connected to form a pipeline element by welding, this was performed in each case taking into consideration only the requirement of pressure tightness. In previous practice, the connections of the hollow bodies to the pipeline element were thus duly connected to one another in a pressure-tight manner. The long-term corrosion resistance known for example from EP 2 766 653 was nevertheless not reliably established.

Accordingly, the invention was based on the object of specifying a method for producing a polymer-enhanced pipeline element which as substantially as possible overcomes the disadvantages described above. In particular, the invention was based on the object of specifying a method of the type described at the outset which, despite the presence of a welded connection, ensures sufficient corrosion resistance in the case of complex pipeline elements.

The invention achieves the object on which it was based, in the case of the method described at the outset, by means of the features described according to the invention. In particular, the method comprises the steps:

-   -   providing a first hollow body and a second hollow body, wherein         the first and second hollow bodies each have a wall, and the         wall has in each case an encircling edge surface,     -   aligning the encircling edge surface of the first hollow body         and the encircling edge surface of the second hollow body with         one another,     -   welding the first hollow body to the second hollow body along         the encircling edge surfaces, wherein a fully encircling weld         seam is generated which has a root extending on the inside of         the pipeline element, and     -   applying a polymer-based layer to the inside of the pipeline         element, wherein the polymer-based layer completely covers the         inside of the pipe element and the root of the weld seam.

The invention is based on the recognition that the pipeline element, by applying a weld seam which extends in fully encircling fashion in the interior of the pipeline element, that is to say in a circle, by contrast to the prior art, the weld seam root generates an advantageous surface geometry which allows complete wetting of the entire inner surface of the pipeline element, including of a transition region from the first to the second hollow body, with the polymer-based protective layer. The root of the weld seam extending in fully encircling fashion ensures a significantly smoother contour transition between the first and the second hollow body in relation to the prior art, such that it is hereby made possible for the first time, using polymer enhancement, for relatively complex pipeline elements, as only single-part pipeline elements, to be provided with long-term corrosion resistance. The smooth contour transition between the first and second hollow bodies offers advantages for any type of polymer enhancement, but makes the pipeline element very particularly suitable for polymer enhancement by means of autodeposition, because the flow conditions in the pipe interior are disrupted to a lesser extent owing to the smooth contour transition. The alignment of the edge surfaces with one another is to be understood to mean that the edge surface of the first hollow body and the edge surface of the second hollow body are oriented and spaced apart relative to one another in such a way that the two hollow bodies can be welded to one another along the edge surfaces.

The method according to the invention is advantageously further developed in that the edge surfaces of the first and second hollow bodies each have an encircling inner edge, and the welding step comprises: forming the root of the weld seam with a thickness which completely encompasses at least one of the inner edges, and preferably both inner edges.

Basically, the suitability of the inside of the pipeline element after the welding for the subsequent coating is more suitable the greater the proportions of the edge surfaces that have been encompassed by the root, because the root achieves a very reliable closure of any previously existing irregularities on the edge by melting, and at the same time has a smoother surface geometry compared to the edge surface of the hollow bodies. Irregularities are to be understood to mean in particular cracks, crevices, capillaries, etc. in the sub-millimeter range, as well as sharp edges. The more such irregularities can be avoided, the better the coating success that is to be expected. According to the invention, it has been found that a satisfactory coating is already achieved if the root completely encompasses only one of the two edge surfaces of the first or second hollow body and a sub-region, in particular a radially inner sub-region, of the other edge surface is not encompassed. It is particularly preferable for both edge surfaces to be completely encompassed. It has been recognized that, even in the prior art, in the case of subsequent polymer enhancement of the pipeline elements, in particular using an autodeposition method, the edges of the pipeline elements have already been coated. Contrary to the previously established opinion, however, this has not yet been achieved with a satisfactory thickness. A further advantage of the invention is evident here: Through the avoidance of sharp edges in the weld seam region that is achieved as a result of the encompassment by the root, better coating also of any remaining edges is also attained. A sharp edge is to be understood to mean an edge angle of less than 90°.

In a preferred embodiment of the method, the root of the weld seam completely encompasses the encircling inner edge of one of the hollow bodies, and the remaining inner edge of the other hollow body is spaced apart from the weld seam by a predetermined maximum value in a radial direction.

Preferably, if identical wall thicknesses are present, the predetermined maximum value is less than or equal to half of a wall thickness of the hollow bodies, particularly preferably less than or equal to one quarter of the wall thickness of the hollow bodies. Alternatively, if different wall thicknesses are present, the maximum value is preferably less than or equal to a difference between the wall thicknesses of the hollow bodies, particularly preferably less than or equal to half of the difference between the wall thicknesses of the hollow bodies.

In a further preferred embodiment of the method, in which the welding step comprises:

forming the root of the weld seam with a thickness which completely encompasses the inner edges of both hollow bodies, the welding is performed such that the root of the weld seam protrudes radially inward from an inside of the wall of the first and/or second hollow body by a predetermined maximum value, wherein the predetermined maximum value preferably amounts to 0.7 times the wall thickness of the hollow bodies or less. By means of the thus ensured but only slight protrusion of the weld seam into the interior of the pipeline element, it can be easily ensured that both edge surfaces have actually been completely encompassed and no cavities or the like remain in the region of the inner edges of the hollow bodies after the welding process. By limiting the maximum height by which the weld seam protrudes inward, it is ensured that the weld seam does not generate any undesired increased flow resistance, which would reduce the C-factor, that is to say the long-term corrosion resistance of the pipeline element.

In a further preferred embodiment, the encircling edge surface of the first hollow body is formed on a face end of the hollow body. More preferably, the encircling edge surface of the second hollow body is spaced apart from the face ends of the second hollow body and defines a cutout through the wall of the second hollow body. This embodiment is present in particular if the first hollow body constitutes a so-called connection element and the second hollow body constitutes a so-called base pipe from which one or more connection elements extend away laterally. In the example of fire extinguishing installations, it is for example the case that sprinklers are connected to these connection elements. A spacing of the edge surface to the face ends of the second hollow body gives rise to a connection of the first and second hollow bodies in the manner of a T-pattern. Preferably, the hollow bodies each have a longitudinal axis, and the longitudinal axes of the hollow bodies are arranged perpendicular to one another or at an angle of +/−5° with respect to the perpendicular. More preferably, the longitudinal axis of the first hollow body is aligned coaxially with respect to a central axis of the cutout.

The spacing between the cutout in the second hollow body and the closest face end preferably lies in a range from 20 cm to 2 m.

As an alternative to the arrangement described above, in a further preferred embodiment the encircling edge surface of the second hollow body is (likewise) formed on a face end of the second hollow body. In this embodiment, it is thus the case that a first and a second hollow body are connected to one another at their respective face ends by welding. This embodiment is particularly preferably to be used if the first and the second hollow body have substantially the same nominal diameter and if elongated base pipe elements are to be generated by welding of the first and second hollow body to one another.

In a further preferred embodiment, the method furthermore comprises the step: generating at least one of the encircling edge surfaces of the first and/or second hollow body by means of cutting, preferably by means of plasma cutting. Plasma cutting has proven to be a highly efficient means of generating the edge surfaces on the hollow bodies, in particular for wall thicknesses of 3.0 mm and above. Precise cuts are possible at high speed and thus with high economic efficiency. Plasma cutting is also suitable for automation of the manufacturing process.

The generated edge surface preferably corresponds to the contour of the respective other hollow body to which the hollow body is to be welded by way of its edge surface. The contour of the edge surface to be generated is preferably determined in advance by measurement, and then the edge surface is generated in a manner dependent on the previously determined contour.

In a further preferred embodiment, the method furthermore comprises the step: cleaning at least one of the encircling edge surfaces, preferably all of the encircling edge surfaces, before the welding, preferably after the cutting, in particular plasma cutting, and before the welding. The cleaning of the edge surfaces comprises in particular the removal of burrs and loose particles, but also of dirt. If the upstream cutting of the edge surfaces was performed by plasma cutting, a metal oxide layer has sometimes formed in the region of the edge surface as a result. It has been recognized in the context of the invention that the cleaning of the edge surface and in particular the removal of metal oxides from the surface of the hollow bodies in the region of the edge surfaces leads to a much more uniform weld pattern and results in a more uniform shape of the root of the weld seam in the interior of the pipeline element. A further advantage of this embodiment is that, firstly, the cleaning of the edge surfaces can be automated with little outlay, in particular if it is performed using a rotationally driven brush. Secondly, the cleaning of the edge surfaces per se also allows an automated welding process, since this is much easier to control in view of the cleaned edge surfaces that have been freed of metal oxides.

In summary, the step of cleaning thus preferably comprises, according to the invention, the removal of metal oxides and loose particles from the at least one encircling edge surface, particularly preferably from all of the edge surfaces, preferably by means of brushes.

In a further preferred embodiment, the method according to the invention furthermore comprises the step: flattening the wall of the first and/or second hollow body in the region in which, in each case, the encircling edge surface extends or is to be generated, preferably before the welding step and more preferably before the cutting step. The flattening may be generated by externally applying a deformation force to the wall of the respective hollow body, for example pneumatically, hydraulically or otherwise mechanically. Optionally, on the underside of the pipeline element, a counterpart half shell of the size of the respective region to be correspondingly flattened can be placed as a counterholder against the hollow body from the outside in order to prevent deformation of the pipeline element at undesired locations, that is to say not at the point where the flattening is to take place. The advantage of the flattening is that the tool for generating the weld seam can perform a substantially flat circular movement and does not have to be guided along a three-dimensional curvature. In this way, on the one hand, the process parameters in the guidance of the welding tool are easier to control, and secondly, the course of the molten metal is easier to control. Since the edge surface runs in a substantially planar manner in the region of the flattening, the edge surface of the corresponding hollow body, which is formed on a face end, can likewise lie in a plane, which in turn simplifies the cutting of the edge surface on the respective hollow body. The flattening is preferably carried out with a predetermined indentation depth, wherein, in preferred embodiments, the depth lies in a range from 0.05 times to 0.18 times the nominal width of the flattened hollow body.

The application of the polymer-based layer is performed in the method according to the invention preferably by dipping of the pipeline element into a dip bath which contains a corresponding coating material. The advantage of a dip coating process is that, in addition to the coating of the particularly sensitive interior region of the pipeline elements, the outer surface is also at least substantially coated in the same coating process.

In a further preferred embodiment, the hollow bodies are formed from a metal suitable for chemical autodeposition, in particular from a ferrous and/or zinc-containing metal, and the step of applying the polymer layer to the inside of the pipeline element comprises: coating, in particular by means of chemical autodeposition, preferably by dipping of the pipeline element into a dip bath which contains a polymer-based chemical autodeposition material. One advantage of using an autodeposition method is inter alia that a uniform, highly corrosion-resistant coating with simultaneously small layer thicknesses is achieved. In particular with the use of a dipping process, a coating can form wherever the pipeline element is wetted. The advantage according to the invention of the optimized weld seams comes to bear again here, because cavities and the like are substantially avoided as a result of the complete, uniform formation of the weld seam in the preferred embodiments described above. A further advantage can be seen in the fact that, owing to the autodeposition layer and the corrosion protection arising therefrom, thinner pipe wall thicknesses are possible that have previously been ruled out owing to the risk of rusting through. Smaller wall thicknesses, in turn, have the advantage that the surface sections occupied by the weld seams in the pipe interior can be further minimized, and that altogether less material has to be applied by welding.

The autodeposition material preferably comprises polymer constituents which are ionically bonded to the wall of the hollow bodies and to the root of the weld seam, and is preferably present as an aqueous emulsion or dispersion.

The autodeposition material is preferably acidic in its liquid phase, and particularly preferably has a pH in a range from 1 to 5, and particularly preferably a starter material in the form of metal halides. In particular iron halides, particularly preferably iron(III) fluoride, are proposed as metal halides for ferrous metals. The metal halides, by reacting on the surface of the pipeline elements, release metal ions, in the case of a ferrous pipeline element that is to say in particular iron ions, in particular Fe2+ ions, which destabilize the polymer constituents in the autodeposition material, resulting in an accumulation on the metal surface of the weld seam and of the hollow bodies.

The autodeposition material preferably has, as polymer constituent, autodepositionable polymers preferably selected from the list comprising:

-   -   i) epoxides,     -   ii) acrylates,     -   iii) styrene acrylates,     -   iv) epoxy acrylates,     -   v) isocyanates, especially urethanes, such as polyurethanes,     -   vi) polymers with a vinyl group, for example polyvinylidene         chloride, or     -   iv) a combination of two or more of i), ii) or iii), which are         preferably crosslinked to one another, more preferably via an         isocyanate, particularly preferably via a urethane.

In the method according to the invention, the dipping step is continued in one or more dipping processes until such time as the polymer-based layer applied to the inside of the pipeline element has a thickness in a range from 7 μm to 80 μm, preferably a thickness in a range from 7 μm to 30 μm. The above-stated values relate to the dry layer thickness and in particular the increase in pipe thickness relative to the uncoated state. It has been found that even layer thicknesses in a range from 7 μm can be applied with the method according to the invention in such a way that complete coverage of the inner surface of the pipeline element and also of a major part of the outer surface, if correspondingly dipped, is realized.

The invention has been described above in a first aspect with reference to the method according to the invention. However, the invention also relates to a pipeline element, in particular produced by a method of the type stated in the introduction. In the case of the pipeline element, the invention achieves the object stated in the introduction in that the pipeline element has: a first hollow body, a second hollow body, wherein the hollow bodies are aligned with one another, and the first and second hollow bodies are connected by means of an encircling weld seam, wherein the weld seam has a root extending on the inside of the pipeline element, and a polymer-based layer on the inside of the pipeline element, wherein the polymer-based layer completely covers the inside of the pipeline element and the root of the weld seam.

The pipeline element according to the invention adopts the advantages and preferred embodiments of the method according to the invention to the full extent, for which reason, to avoid repetition, reference is made to the statements above.

In a preferred refinement of the pipeline element, the root of the weld seam completely encompasses an edge surface of one of the hollow bodies, and the pipeline element has, in the interior, a remaining inner edge of the other hollow body, which remaining inner edge is spaced apart from the weld seam by a predetermined maximum value in a radial direction.

Preferably, if identical wall thicknesses are present, the predetermined maximum value is less than or equal to half of a wall thickness of the hollow bodies, particularly preferably less than or equal to one quarter of the wall thickness of the hollow bodies. Alternatively, if different wall thicknesses are present, the maximum value is preferably less than or equal to a difference between the wall thicknesses of the hollow bodies, particularly preferably less than or equal to half of the wall thicknesses of the hollow bodies.

In a preferred embodiment, the root of the weld seam completely encompasses the edge surfaces of both hollow bodies, and protrudes radially inward from an inside of the first and/or second hollow body by a predetermined maximum value, wherein the predetermined maximum value preferably amounts to 0.7 times the wall thickness of the hollow bodies or less.

In a further preferred embodiment, the wall of the first hollow body is welded at one face end to a region of the wall of the second hollow body, which region is spaced apart from the face ends of the second hollow body and in which region a cutout extends through the wall. Such an arrangement of the first and second hollow bodies is also referred to as a T-arrangement. Such an arrangement is preferred in particular if the pipeline element has a connection element as the first hollow body and a main or base pipe as the second hollow body, from which one or more connection elements extend away laterally. The connection elements will be specified in more detail further below. Preferably, the hollow bodies each have a longitudinal axis, and the longitudinal axes of the hollow bodies are arranged perpendicular to one another or at an angle of +/−5° with respect to the perpendicular. More preferably, the longitudinal axis of the first hollow body is aligned coaxially with respect to a central axis of the cutout.

The spacing between the cutout in the second hollow body and the closest face end preferably lies in a range from 20 cm to 2 m.

In an alternative preferred embodiment, the walls of the first and of the second hollow body are welded to one another in each case at a face end of the respective hollow body. In this embodiment, the hollow bodies are thus welded to one another in each case at an end side, for example in order to generate a pipeline element with a particular length that exceeds the size of the respective hollow bodies. The welding of the hollow bodies in the manner according to the invention is, in this embodiment, particularly preferred for those embodiments in which the first and second hollow bodies have identical or almost identical nominal diameters. Here, nominal diameter deviations in the range of up to 10% can generally be tolerated.

In a further preferred embodiment, the wall of the second hollow body is flattened in a region around the cutout. In other words, the second hollow body is flattened in that wall region in which the first hollow body is also to be attached. This has the advantage that the corresponding edge surface of the first hollow body can be made substantially planar and does not need to have a three-dimensional curvature with which the first hollow body would otherwise have to lie closely against the wall, because the wall is likewise substantially planar in the region of the flattenings.

In a further preferred embodiment, the hollow bodies are formed from a metal suitable for chemical autodeposition, in particular from a ferrous and/or zinc-containing metal, and the polymer-based layer contains a metallic constituent, preferably in the form of metal ions, that is to say particularly preferably in the form of iron ions in the case of a ferrous metal and in the form of zinc ions in the case of a zinc-containing metal.

The autodeposition material preferably has, as polymer constituent, autodepositionable polymers preferably selected from the list comprising:

-   -   i) epoxides,     -   ii) acrylates,     -   iii) styrene acrylates,     -   iv) epoxy acrylates,     -   v) isocyanates, especially urethanes, such as polyurethanes,     -   vi) polymers with a vinyl group, for example polyvinylidene         chloride, or     -   iv) a combination of two or more of i), ii) or iii), which are         preferably crosslinked to one another, more preferably via an         isocyanate, particularly preferably via a urethane.

In a further preferred embodiment, the polymer-based layer has a thickness in a range from 7 μm to 80 μm, particularly preferably a thickness in a range from 7 μm to 30 μm. This in turn relates to the dry layer thickness and in particular to an increase in thickness relative to the uncoated state.

Preferably, the second hollow body is of tubular form and has a nominal diameter in a range from DN 15 to DN 300, preferably DN 32 to DN 80. Alternatively, the nominal width ranges in the inch system lie from ½″ (NPS) to 12″ (NPS), particularly preferably in a range from 1¼″ (NPS) to 3″ (NPS).

Preferably, the second hollow body has a longitudinal axis and a pipe length in the direction of the longitudinal axis in a range of 1 m or more, more preferably in a range of 3 m or more, particularly preferably in a range of 5 m or more.

It is furthermore preferable if the first hollow body is likewise of tubular form and has a nominal diameter which is equal to the nominal diameter of the second hollow body or less than the nominal diameter of the second hollow body.

The first hollow body is preferably selected from the list comprising:

-   -   pipe,     -   connector,     -   flange,     -   closure cap,     -   reduction piece,     -   bend, or nipple.

Preferably, on the first hollow body, there is formed a fastening element, preferably selected from the list comprising:

-   -   thread;     -   groove; or     -   flange ring.

The fastening element is preferably configured for connecting fluid discharge devices, such as extinguishing nozzles, sprinklers, fluid distributors or other pipeline elements, to the first hollow body. The fastening element is preferably formed at least partially from one of the abovementioned metals suitable for chemical autodeposition, in particular a ferrous and/or zinc-containing metal, and at least partially provided with the polymer-based layer.

The invention has been described above with reference to a pipeline element and a production method for the pipeline element. In a further aspect, the invention also relates to a pipeline system of a fire extinguishing installation, having a number of pipeline elements which are coupled to one another, wherein one, multiple or all pipeline elements have been designed or produced in accordance with one of the preferred embodiments described above. The preferred embodiments and advantages according to the invention of the production method and of the pipeline element according to the invention are at the same time the advantages and preferred embodiments of the pipeline system according to the invention, for which reason reference is made in this regard to the present statements in order to avoid repetition.

It is particularly preferable if one, multiple or all of the pipeline elements has a first hollow body of tubular form and a second hollow body of tubular form, wherein the nominal diameter of the first hollow body is equal to or less than the nominal diameter of the second hollow body, and wherein, in each case, a sprinkler, an extinguishing nozzle, a fluid distributor or a further pipeline element is connected to that face side of the first hollow body which is averted from the weld seam between the two hollow bodies.

The invention furthermore also relates to the use of a pipeline element in a pipeline system of a fire extinguishing installation, in which a number of pipeline elements are coupled to one another, wherein in each case one, multiple or all pipeline elements is or are designed in accordance with one of the preferred embodiments described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail below with reference to the accompanying figures and with reference to preferred exemplary embodiments.

FIG. 1 shows a schematic method flow diagram of the method according to the invention according to a preferred exemplary embodiment.

FIG. 2 is a schematic three-dimensional illustration of a pipeline element produced in accordance with the method according to FIG. 1.

FIGS. 3a, b show side views of the pipeline element as per FIG. 2.

FIGS. 4a-e and FIGS. 5a-e are detail illustrations of various preferred variants of the pipeline element as per FIGS. 2 and 3 a, b.

FIG. 6 is a further detail illustration relating to FIG. 5 c.

FIG. 7 is a further detail illustration relating to FIGS. 5 b, d.

FIG. 8 is a schematic illustration of a hollow body flattened in certain regions.

FIG. 9 is a schematic partial illustration of a pipeline element according to a further preferred exemplary embodiment, produced in accordance with the method as per FIG. 1.

MODE(S) FOR CARRYING OUT THE INVENTION

FIG. 1 illustrates the schematic sequence of the method according to the invention for producing a polymer-enhanced pipeline element according to a preferred exemplary embodiment. Firstly, in steps 1 a, 1 b, a first hollow body and a second hollow body are provided. Subsequently, in a next method step 3 a, b, edge surfaces are provided on the hollow bodies, preferably by means of plasma cutting. In steps 3 a, b, the hollow bodies are provided with edge surfaces either on one or both of their end faces or on a wall section which is spaced apart from the respective end faces, said wall section being in the form of a cutout.

In a subsequent method step 5 a, b, the first and second hollow bodies are cleaned on the edge surfaces, preferably by means of a rotationally driven brush. If plasma cutting was used in the previous step to generate the edge surfaces, metal oxides and loose particles and burrs formed as a result of the brushing are removed as substantially as possible.

In a next method step, the first hollow body and the second hollow body are aligned with one another such that in each case one edge surface of one hollow body is aligned and arranged as closely adjacent as possible to a corresponding edge surface of the respective other hollow body. The alignment of the hollow bodies with respect to one another may be performed manually or by means of single-jointed or multi-jointed robots.

In a next method step 9, the previously aligned hollow bodies are welded to one another along the mutually aligned encircling edge surfaces, such that a fully encircling weld seam is generated which has a root extending on the inside of the pipeline element. A single-layer weld seam is preferably applied.

Following the welding, the welded-together hollow bodies are, in a method step 21 which may in turn have several sub-steps not illustrated in detail, prepared for the subsequent coating. The preparation comprises the cleaning of the welded-together hollow bodies in one or more dip baths in which, for example, pickling or rinsing media such as demineralized water can be stored. The exact number and arrangement of the preparatory steps depends on the specifications of the coating material to be used.

The welded hollow bodies prepared in step 21 are then chemically coated in a next method step 23 in one or more dipping operations by means of an autodeposition method. The result of the dipping is that the entire inside including the weld seam, but also the outside of the hollow bodies, is substantially completely coated.

Following the coating of the hollow bodies and of the weld seam with the polymer-based layer, a thermal aftertreatment process takes place in a step 25. The step 25 may include one or more substeps, in each of which a flash-off or tempering with predetermined temperatures and tempering periods is performed (low-temperature tempering or high-temperature tempering). Optionally, the pipeline elements coated and aftertreated in this way, which have been generated from the hollow bodies, may be powder-coated in a step 27. The powder coating is also preferably cured in a thermal aftertreatment process in step 25.

Subsequently, in step 29, the pipeline element is conveyed out of the production process and is ready for use.

The method step 25 for the thermal aftertreatment of the pipeline elements is shown as a single step for the sake of simplicity. It is however possible for multiple successive heat treatment stages to be performed in step 25, which are performed in one or in multiple different devices.

The welding process according to step 9 may for example be optimized in that, in a measuring step 13, which may be performed at any time between steps 1 a, b and the welding step 9, the diameters of the hollow bodies and the wall thicknesses of the hollow bodies, in particular in the region of the edge surfaces, are measured. Optionally, a measurement is carried out online, for example optically by means of gap detection, directly in the method step of the edge surface generation, and, on the basis of the measured variables, the welding parameters are then adapted online in order to compensate for any deviations of the measured geometry from the starting geometry for which the original welding parameters were stored. This makes it possible for the effects of the deviations, for example any out-of-roundness of the hollow body, to be compensated in the welding process itself.

Depending on the measured parameters, a parameter set for optimal application of the weld seam is preferably selected in a method step 15 from a predefined value table. The parameters that are stored in the predefined value table for each diameter and each wall thickness preferably comprise the feed rate, the path of the welding tool, the selection of a welding filler material and, in the case of arc welding, the voltage to be applied, the feed rate of the welding wire, etc.

In a subsequent step 17, the previously determined parameters are preferably read into the welding tool or, if welding is to be performed manually, provided to the operator in order that the welding of the first and second hollow bodies to one another can be performed in the subsequent step 19.

The method has been discussed schematically with reference to FIG. 1. The pipeline element generated by means of the method, to which reference has in part already been made, will be discussed in more detail in FIGS. 2 to 5 a-e on the basis of several variants.

FIG. 2 firstly shows a pipeline element 100 which has a first hollow body 101 and a second hollow body 102.

The first hollow body 101 has a first face end 103 and a second face end 105, at which it is welded to the second hollow body 102. At the point at which it is welded to the first hollow body 101, the second hollow body 102 has a cutout (113, cf. FIG. 4) in its side wall 107.

The first hollow body 101 and the second hollow body 102 are connected by means of a single-layer, fully encircling weld seam 109.

In the interior of the pipeline element 100, the pipeline element 100 has a polymer-based layer 111 which extends all the way along the insides of the hollow bodies 101, 102 and which also at any rate completely covers the encircling weld seam 109 on the inside of the pipeline element 100. If the pipeline element has been coated in a dipping process, the outer surface of the first and second hollow bodies 101, 102 and the weld seam 109 are at least substantially covered by the polymer-based layer.

In the exemplary embodiment shown, the first hollow body 101 is arranged approximately centrally between a first face end 108 and a second face end 110 of the second hollow body 102 and, as can be seen in particular in FIGS. 3 a, b, is aligned as far as possible coaxially with respect to a cutout 113 formed in the side wall 107 of the second hollow body 102. The first hollow body 101 and the second hollow body 102 are aligned at an angle α with respect to one another, which angle may for example lie in a range around 90°.

FIGS. 4a-e and 5a-e show various details relating to the positioning of the hollow bodies relative to one another and relating to the selection of the form of the weld seam, in each case along the section plane A-A.

FIGS. 4a to e show different arrangement variants of the first and second hollow bodies 101, 102 with respect to one another, and with them also different scenarios for the specific shape of the weld seam in the interior of the pipeline element 100 (cf. FIGS. 1 to 3 b). FIGS. 4a to e have in common the fact that the first main body has an edge surface 115 at its second face end 105, and the second hollow body 102 has an edge surface 117 delimiting the cutout 113. The embodiments of FIGS. 4a to 4e differ primarily with regard to the arrangement of the edge surfaces 115, 117 with respect to one another.

FIG. 4a firstly shows that the edge surface 115 of the first hollow body 101 protrudes into the opening 113 defined by the edge surface of the second hollow body 102. Preferably, the first hollow body 101 and the second hollow body 102 are aligned with one another, and the cutout 113 in the second hollow body 102 is dimensioned, such that the edge surface 115 of the first hollow body 101 is connected only at the outer encircling edge to the second hollow body 102, or extends entirely within the cutout 113. In this way, in order to attain a fully encircling weld seam, only relatively material has to be melted on, and rapid working operation is made possible. In the ideal case, with an arrangement as per FIG. 4a , a weld seam as illustrated in FIG. 5a can be generated. Here, the “ideal case” is to be understood to mean a correct selection of a predefined set of parameters which take into consideration the exact dimensions of the hollow bodies 101 and 102 and the position of the edge surfaces 115, 117.

By contrast to FIG. 4a , in FIG. 4b the first hollow body is selected to be somewhat larger in terms of its diameter, at any rate relative to the diameter of the cutout 113. The edge surface 115 lies against the outside of the second hollow body 102. The inside of the wall of the first hollow body 101 preferably terminates flush with the edge surface 117 of the cutout 113 in the second hollow body 102. With alignment and dimensioning as per FIG. 4b , a welding pattern as per FIGS. 5b, d is obtained if a corresponding set of parameters is selected.

In FIG. 4c , an alignment between the first hollow body 101 and the second hollow body 102 has been performed substantially as in FIG. 4a , such that the edge surface 115 lies with an externally encircling edge against the edge surface 117 of the second hollow body 102 or is adjacent to the latter there.

By contrast to FIG. 4a , however, the material thickness of the first hollow body 101 is greater, such that a weld pattern as per FIG. 5c will be established in each case again if the correct set of parameters is selected.

FIG. 4d differs from FIG. 4b with regard to the dimensioning of the first hollow body relative to the second hollow body. In qualitative terms, the same weld pattern is to be expected here, for which reason reference is made to the statements above and to FIGS. 5 b, d.

FIG. 4e in turn shows an alignment of the first and second hollow bodies 101, 102 relative to one another as were also already selected in FIGS. 4a and 4c . By contrast to FIGS. 4d and 4c , the material thickness of the second hollow body 102 has however been selected such that a weld pattern as per FIG. 5e is established, provided that the correct set of parameters is selected.

As can be seen from FIG. 5a , in the case of the alignment shown in FIG. 4a , the hollow bodies 101 and 102 are in the ideal case completely encompassed at edge surfaces 115, 117 by a root 112 of the weld seam 109, such that a smooth transition between an inside 118 of the first hollow body 101 and an inside 119 of the second hollow body 102 is generated. The polymer-based layer 111 can ideally be applied to this geometry. In FIGS. 5 b, d, the root 112 of the weld seam 109 likewise runs around the entire circumference along the connection point between the first hollow body 101 and the second hollow body 102. By contrast to FIG. 4a , however, only the edge surface 115 of the first hollow body 101 has been completely encompassed by the weld seam 109, whereas the edge surface 117 of the second hollow body 102 has been only partially encompassed. Owing to the alignment and dimensioning between the first hollow body 101 and cutout 113, the root 112 of the weld seam 109 however projects radially inward from the wall 118 of the first hollow body 101 only by a predetermined maximum value h1. h1 preferably lies in a range of 0.7 times the material thickness of the wall 107 or less. The weld seam therefore does not constitute an obstacle to the complete wetting of the inside of the pipeline element with the polymer-based layer 111.

FIG. 5c illustrates a variant in which, owing to the material thickness of the first hollow body 101, not the entire edge surface 115 of the first hollow body 101 has been encompassed by the root 112 of the weld seam 109, such that a part, specifically in the region of an inner edge 121, protrudes radially inward from the weld seam 109 in relation to the first hollow body 101. However, as long as the inner edge 121 is spaced apart from the weld 109 by no more than a predetermined maximum value h2, the threshold for the flow resistance resulting from the remaining edge surface 115 is within tolerable limits. Furthermore, complete wetting of the inside of the pipeline element with the polymer-based layer 111 is not significantly impaired as a result. The value h2 preferably lies in a range of 0.5 times the difference in the wall thickness of the walls 107, if they have the same wall thickness, or less. Alternatively, h2 is preferably less than the difference between the two wall thicknesses of the hollow bodies 101, 102, if the wall thicknesses are different from one another.

In order to obtain a weld pattern as in FIG. 5c , an alignment of the hollow bodies 101, 102 as per FIG. 6 is preferably selected. It is particularly preferable if the edge surface 115 of the first hollow body 101 and/or the edge surface 117 of the second hollow body 102 is bevelled. In this way, the amount of material to be melted on is significantly reduced. Since the material thickness in the region of the weld seam 109 to be generated may be very small, it is advantageous to introduce a bath support 200 into the second hollow body 102, which bath support prevents sagging of the molten metal.

FIG. 5e is an illustration analogous to FIG. 5c , in which, owing to the material thickness of one of the hollow bodies, in this case of the second hollow body 10, no complete encompassment of both edge surfaces of the first hollow body 101 and of the second hollow body 102 is realized. In this case, it is an inner edge 123 at the cutout 113 in the second hollow body 102 that is spaced apart from the root 112 of the weld seam 109 by a predetermined value h3, such that a part of the edge surface 117 of the second hollow body 102 is still visible. However, if the value h3 does not exceed a predetermined maximum value, preferably determined as h2 above, the complete formation of a polymer-based layer 111 is not hindered, and also the flow conditions are not inadmissibly impaired. The advantages of the embodiments as per FIGS. 5c and e lie in technically significantly easier controllability. The diameter and material thickness tolerances of the first hollow body 101 and the second hollow body 102 can be dimensioned more generously than in the embodiments of FIGS. 5a and 5 b, d, which simplifies the preselection of suitable sets of parameters.

In order to obtain a weld pattern as per FIGS. 5b and d, alignment and preparation of the hollow bodies 101, 102 as per FIG. 7 is preferably performed. The first hollow body 101 preferably has, on its edge surface 115, a number of projections 125, which may for example be formed as pins and which specify a predefined gap spacing to the second hollow body 102 when the two hollow bodies 101, 102 have been aligned with one another as shown in FIG. 7. The projections ensure that the gap spacing between the hollow bodies 101, 102 remains constant during the welding process, and facilitate the creation of a weld seam 109 with at least the edge surface 115 of the first hollow body 101, or even the edge surfaces 115, 117 of both hollow bodies 101, 102, being completely encapsulated by the root.

Finally, FIG. 8 shows the aspect of the local flattening based on the example of the second hollow body 102. The second hollow body 102 has, over a region B, been indented by a depth T, for example by means of a pressing tool. In the flattened region B, the wall 107 of the second hollow body 102 is substantially planar. In this way, it is possible for the edge surface 115 of the first hollow body 101 to be formed as a likewise planar end surface, which is advantageous in terms of manufacturing economy. The weld seam 109 accordingly likewise extends in a substantially planar manner in the flattened region B along the circumference of the edge surface 115. The depth T is preferably a function of the material thickness of the wall 107 of the second hollow body and of the nominal width of the first hollow body 101. In preferred embodiments, the depth T lies in a range from 0.05 times to 0.18 times the nominal width of the flattened hollow body, that is to say of the hollow body 102 in FIG. 8.

In the figures described above, the invention has been described, in a first aspect, as being such that the first hollow body 101 constitutes a connector element and the second hollow body 102 is a main pipe. FIG. 9 now illustrates a pipeline element 100 with an encircling weld seam 109, in the case of which both the first hollow body 101 and the second hollow body 102 are each a main pipe. The hollow bodies 101 and 102 are arranged coaxially with respect to one another and axially adjacent to one another. In the non-welded state, the hollow bodies 101 and 102 each have an edge surface 115, 117 facing toward the other hollow body. After the application of the weld seam 109 in accordance with the invention, a root 112 of the weld seam 109 extends in fully encircling fashion in a circle within the pipeline element 100.

In the non-welded state, the edge surfaces 115, 117 are still each delimited by an encircling inner edge 121, 123. The encircling inner edges 121, 123 are, in the welded state, completely encompassed by the root 112 of the weld seam 109. Instead of an angular, sharp transition between the hollow bodies 101, 102, the root 112 of the weld seam forms a relatively smooth transition. Here, the root 112 of the weld seam 109 protrudes radially within the wall 107 of the pipeline element 100 by a predetermined maximum value h1. The extent to which the root 112 protrudes inward preferably amounts to 0.7 times the material thickness of the wall 107 of the hollow bodies or less.

In the course of preliminary tests, it is ascertained for the predetermined pipe diameter what welding parameters can be used to form the root 112 with the desired height h1, see above. Depending on what pipe diameter is present for the respectively present order, the suitable parameter set is selected from the previously determined list and the welding process is performed using said parameter set. The approach here is basically the same irrespective of whether the welding is performed in automated, partially automated or manual fashion.

In the interior, the pipeline element 100 as per FIG. 9 likewise has a polymer-based layer 111 which extends all the way along the insides of the hollow bodies 101, 102 and which also at any rate completely covers the encircling weld seam 109 on the inside of the pipe 100. If the pipeline element has been coated in a dipping process, the outer surface of the first and second hollow bodies 101, 102 and the weld seam 109 are also at least substantially covered by the polymer-based layer 111.

In summary, with the invention, it has been possible for the first time to expand the field of application of polymer enhancement to also include complex pipeline elements with one or more welded connections. Where the prior art has hitherto still prevented successful coating on the inside of the pipeline elements owing to poor quality of the weld seams, the invention proposes an advantageous further development. 

1. A method for producing a polymer-enhanced pipeline element of a fire extinguishing installation, the method comprising: providing a first hollow body and a second hollow body, wherein the first and second hollow bodies each have a wall, and the wall has in each case an encircling edge surface, aligning the encircling edge surface of the first hollow body and the encircling edge surface of the second hollow body with one another, welding the first hollow body to the second hollow body along the encircling edge surfaces, wherein a fully encircling weld seam is generated which has a root extending on the inside of the pipeline element, and applying a polymer-based layer to the inside of the pipeline element, wherein the polymer-based layer completely covers the inside of the pipe element and the root of the weld seam.
 2. The method as claimed in claim 1, wherein the encircling edge surfaces of the first hollow body and of the second hollow body comprise an encircling inner edge, and the welding further comprises: forming the root of the weld seam with a thickness that completely encompasses at least one or both inner edges.
 3. The method as claimed in claim 2, wherein the root of the weld seam completely encompasses the encircling inner edge of one of the hollow bodies, and the remaining inner edge of the other hollow body is spaced apart from the weld seam by a predetermined maximum value in a radial direction.
 4. The method as claimed in claim 3, wherein the predetermined maximum value comprises: a) if the first and second hollow bodies have the same wall thickness, is less than or equal to half of a wall thickness of the hollow bodies, or b) if the first and second hollow bodies have different wall thicknesses, is less than or equal to a difference between the wall thicknesses of the hollow bodies.
 5. The method as claimed in claim 2, wherein the welding further comprises: forming the root of the weld seam with a thickness which completely encompasses the inner edges of both hollow bodies, wherein the root of the weld seam protrudes radially inward from an inside of the wall of the first and/or second hollow body by a predetermined maximum value, wherein the maximum value amounts to 0.7 times the wall thickness of the hollow bodies or less.
 6. The method as claimed in claim 1, wherein the encircling edge surface of the first hollow body is formed at a face end of the hollow body.
 7. The method as claimed in claim 6, wherein the encircling edge surface of the second hollow body is spaced apart from face ends of the second hollow body and defines a cutout through the wall of the second hollow body.
 8. The method as claimed in claim 6, wherein the encircling edge surface of the second hollow body is formed at a face end of the second hollow body.
 9. The method as claimed in claim 7, furthermore comprising: generating at least one of the encircling edge surfaces of the first and/or second hollow body by plasma cutting.
 10. The method as claimed in claim 9, furthermore comprising: cleaning the encircling edge surface or edge surfaces before the welding, after the plasma cutting.
 11. The method as claimed in claim 10, wherein the cleaning comprises removing metal oxides and loose particles from the at least one encircling edge surface by brushing.
 12. The method as claimed in claim 5, furthermore comprising: flattening the wall of the first and/or second hollow body in the region in which, in each case, the encircling edge surface extends or is to be generated, before the welding and/or before the cutting.
 13. The method as claimed in claim 1, wherein the application of the polymer-based layer is performed by dipping of the pipeline element into a dip bath which contains a corresponding coating material.
 14. The method as claimed in claim 1, wherein the hollow bodies are formed from a metal suitable for chemical autodeposition including a ferrous and/or zinc-containing metal, and the applying the polymer layer to the inside of the pipeline element comprises: coating by chemical autodeposition, which includes dipping of the pipeline element into a dip bath which contains a polymer-based chemical autodeposition material.
 15. The method as claimed in claim 14, wherein the autodeposition material comprises polymer constituents which are ionically bonded to the wall of the hollow bodies and to the root of the weld seam, and is preferably present as an aqueous emulsion or dispersion.
 16. The method as claimed in claim 14, wherein the autodeposition material is acidic, has a pH value in a range from 1 to 5, and comprises a starter material in the form of metal halides.
 17. The method as claimed in claim 14, wherein the autodeposition material has, as polymer constituent, one or more autodepositionable polymers selected from the list comprising: i) epoxides, ii) acrylates, iii) styrene acrylates, iv) epoxy acrylates, v) isocyanates, urethanes, and/or polyurethanes, vi) polymers with a vinyl group and/or polyvinylidene chloride, or iv) a combination of two or more of i), ii) or iii), which are crosslinked to one another, via an isocyanate and/or via a urethane.
 18. The method as claimed in claim 14, wherein the dipping is continued in one or more dipping processes until such time as the polymer-based layer applied to the inside of the pipeline element has a thickness in a range from 7 μm to 80 μm.
 19. A pipeline element comprising: a first hollow body, a second hollow body, wherein the hollow bodies are aligned with one another, and the first and second hollow bodies are connected by an encircling weld seam, wherein the weld seam comprises a root extending on the inside of the pipeline element, and a polymer-based layer on the inside of the pipeline element, wherein the polymer-based layer completely covers the inside of the pipeline element and the weld seam.
 20. The pipeline element as claimed in claim 19, wherein the root of the weld seam completely encompasses an edge surface of one of the hollow bodies, and the pipeline element has comprises, in the interior, a remaining inner edge of the other hollow body, which remaining inner edge is spaced apart from the weld seam by a predetermined maximum value in a radial direction.
 21. The pipeline element as claimed in claim 20, wherein the predetermined maximum value comprises: a) if the first and second hollow bodies have the same wall thickness, is less than or equal to one quarter of the wall thickness of the hollow bodies, or b) if the first and second hollow bodies have different wall thicknesses, is less than or equal to half of the difference between the wall thicknesses of the hollow bodies.
 22. The pipeline element as claimed in claim 19, wherein the root of the weld seam completely encompasses the edge surfaces of both hollow bodies, and protrudes radially inward from an inside of the wall of the first and/or second hollow body by a predetermined maximum value, wherein the predetermined maximum value amounts to 0.7 times the wall thickness of the hollow bodies or less.
 23. The pipeline element as claimed in claim 19, wherein the wall of the first hollow body is welded at one of its face ends to a region of the wall of the second hollow body, which region is spaced apart from face ends of the second hollow body and in which region a cutout extends through the wall.
 24. The pipeline element as claimed in claim 19, wherein the walls of the first hollow body and of the second hollow body are welded to one another in each case at a face end of the respective hollow body.
 25. The pipeline element as claimed in claim 23, wherein the wall of the second hollow body is flattened in a region around the cutout.
 26. The pipeline element as claimed in claim 19, wherein the hollow bodies are formed from a metal suitable for chemical autodeposition, including a ferrous and/or zinc-containing metal, and the polymer-based layer contains a metallic constituent, in the form of iron ions and/or zinc ions.
 27. The pipeline element as claimed in claim 26, wherein the autodeposition material has, as polymer constituent, one or more autodepositionable polymers selected from the list comprising: i) epoxides, ii) acrylates, iii) styrene acrylates, iv) epoxy acrylates, v) isocyanates, urethanes, and/or polyurethanes, vi) polymers with a vinyl group, and/or polyvinylidene chloride, or iv) a combination of two or more of i), ii) or iii), which are crosslinked to one another via an isocyanate and/or via a urethane.
 28. The pipeline element as claimed in claim 27, wherein the polymer-based layer has a thickness in a range from 7 μm to 80 μm.
 29. The pipeline element as claimed in claim 19, wherein the second hollow body is of tubular form and has a nominal diameter in a range from DN 15 to DN
 300. 30. The pipeline element as claimed in claim 19, wherein the second hollow body has a longitudinal axis and a pipe length in the direction of the longitudinal axis in a range of 5 m or more.
 31. The pipeline element as claimed in claim 30, wherein the first hollow body comprises a tubular form and has a nominal diameter which is equal to a nominal diameter of the second hollow body or less than the nominal diameter of the second hollow body.
 32. The pipeline element as claimed in claim 19, wherein the first hollow body is selected from the list comprising: pipe, connector, flange, closure cap, reduction piece, bend, or nipple.
 33. The pipeline element as claimed in claim 32, wherein, on the first hollow body, there is formed a fastening element selected from the list comprising: thread; groove; and/or flange ring; wherein the fastening element is configured to connect fluid dispensing devices including extinguishing nozzles, sprinklers, fluid distributors or other pipeline elements to the first hollow body, and/or is at least partially formed from a metal suitable for chemical autodeposition including a ferrous and/or zinc-containing metal, and is at least partially provided with the polymer-based layer.
 34. A pipeline system of a fire extinguishing installation, having a number of pipeline elements which are coupled to one another, wherein one, multiple or all pipeline elements are as claimed in claim
 19. 35. (canceled) 